Cable Car

Father with his two children walking at the path which lies below wires of cable car from it's base to the top of the mountain. When they rested on the trip, the father said: "We are now at the half way of the mountain", where he learned this?
Both the cable car that relies on the wire and with elektromotor mobilized at the base of the mountain - drawn endless wire, up and down the mountain. In this movement up and down the train carriage counterweight. So the two trains that depart from the top and bottom at the same time and met right in the middle of the road.